Study Of Adsorption Refrigeration Using Activated Carbon-ammonia Of Powered By Ship’s Waste Heat

Due to the unstability of silica gel, noxious decomposition of methanol, high temperature ofheating source for driving molecular sieve, hardening and dusting plug of metal chloride andother issues, the working pair activated carbon-ammonia was selected for adsorptionrefrigeration and air conditioning system driven by ship’s waste heat, researches included in thispaper are as follows:1) Analysis of the effect of physical properties of activated carbon on its adsorptioncapacity of ammonia. SAC activated carbon samples produced from the coconut shell wereselected as adsorbents, and Autosorb-1MP type from Quantachrome was employed tocharacterize the structure of the adsorbent in terms of specific surface area, pore size distributionand specific pore volume. Isotherms of ammonia adsorption were volumetrically measured attemperature303K within the pressure range of0-1.12MPa. It shows that the specific surface areaand mean pore width as well as specific pore volume of the adsorbents were800m~2/g-1960m~2/g,2.07nm-2.27nm and0.032mL/g-0.197mL/g respectively; the adsorption amount of ammonia onthe activated carbon increases in the specific surface area, and the maximum amount ofadsorption is about498mg/g on the SAC-02activated carbon having the specific surface area1960m~2/g.2) Analysis of the adsorption-desorption equilibrium of Ammonia on the activated carbon.Firstly, the adsorption equilibrium data of ammonia was measured on SAC-02activated carbonat the temperatures from293K to318K and the pressures from0MPa to1.12MPa, and thecorresponding adsorption capacity of ammonia was calculated by the Virial equation. Secondly,the outcomes from experiments was used to determine parameters in DA equation by way ofnonlinear fit, the predictive accuracy of DA equation was analyzed after its parameters werecalibrated. Thirdly, the isosteric heat of ammonia adsorption on the activated carbon wasdetermined by the adsorption isosteres plotting and Clausius-Clapeyron equation withinadsorption amount range of255mg/g-385mg/g, the limit isosteric heat of ammonia adsorption onactivated carbon was studied by Henry’s law plotting of the adsorption data at the low pressurearea. Conclusions are drawn that predictive accuracy of DA equation is relate to pressure, thepredictive value with a larger relative error at the low pressure area, while it maintains a relativeerror of less than6%in the pressure range of0.15MPa-1.03MPa, the heat of ammonia adsorption on SAC-02activated carbon is in range of24.25kJ mol1-38.04kJ mol1. Finally,analysis of the effect of heat source on the desorption rate of ammonia was carried out on anadsorption bed packing with SAC-02activated carbon about69.908g and in thickness31mm, itwas found that when the temperature of heat source is increased from80℃to120℃, the averagerate of desorption will be increased from1.46mg/s to2.49mg/s.3) Research of ammonia adsorption refrigeration system driven by waste heat of typicalship."SITC TAISHAN" bulk carrier which has total load capacity58107tons was selected,analysis of energy balance of the main engine of the ship was carried out at its typical workingcondition. Based on currently coefficient of performance in activated carbon-ammoniaadsorption refrigeration system the amount of waste heat contained within the exhaust gas wasused to evaluate the feasibility of applying the adsorption refrigeration on board the ship.Secondly, the shell and tube type of adsorption bed was used to design the multi-bed continuousrefrigeration cycle system in line with the structure of ship’ cabin and the tested data of ammoniaadsorption on activated carbon, and plate heat exchanger was accordingly selected for theevaporator and condenser. In additions, variation curve between the flow rate of cooling water ofcondenser and the heat of adsorption were analyzed quantitatively.